This invention relates to elastomeric seals for pipes and, more particularly to an elastomeric seal for sealing pressure conditions on a stationary pipe.
Frequently it is necessary to circulate a liquid or gas under pressure, or to transmit pressure through a medium from one point to another through a tube to energize controls or produce a pressure related event. Occasionally, the only conection between the fluid-carrying pipe and the chamber or structure into which the fluid is injected is the seal around the pipe. In such applications, the pipe seal must function efficiently to facilitate assembly as well as to prevent fluid leakage.
Elastomeric seals in a wide variety of configurations have been provided for achieving a seal between a rotating shaft and a housing wherein a pressurized fluid environment is located on one side of the seal. A prior art search has revealed the following U.S. Pat. Nos. 1,598,501; 1,969,797; 2,209,578; 2,348,587; 2,692,785; 2,804,325; 2,858,150; 2,893,770; 3,049,357; 3,394,939; 3,601,418; and 3,940,155. With the exception of U.S. Pat. No. 2,348,587, which teaches a seal for a spherical ball joint, all of the references cited relate to seals for a shaft which rotates or reciprocates relative to another part. The cited references disclose seals having only a single, annular sealing zone and other seals having multiple sealing zones, such as, U.S. Pat. Nos. 2,858,150; 3,049,357; 3,394,939; and 3,940,155.
For ease of assembly operations, it is desirable that, a cylindrical or annular seal be simply press fittable into its associated bore and there be retained under intended operating conditions. Elastomeric materials, such as rubber or suitable compressible plastics, are lacking in the rigidity necessary to enable such easy placement and retention. In an effort to overcome this problem, U.S. Pat. No. 2,692,785 discloses a seal having a rigid metallic shell and an elastomeric sealing member bonded thereto. However, that structure nonetheless has the elastomeric material, which is subject to wear and compression fatigue, in contact with the bore in which it is positioned.
More recently, there have been utilized pipe seals having a cylindrical rigid metal shell and an elastomeric material bonded only to the inner surface of that shell. The elastomeric material was shaped to afford two zones of sealing area on the pipe. It was found, however, that during operational assembly and insertion of the pipe through the seal, the pipe had a tendency to snag or catch on one of the elastomeric lips with the result that one of the zones of sealing was damaged or rendered ineffective.
There thus exists a need for a pipe seal of simple yet sturdy construction which is press-fittable into zones and means for facilitating the operational assembly of the pipe therethrough.